Wet clutches are used to provide a mechanical by-pass for hydrodynamic coupling in torque converters in order to improve fuel economy for vehicles including the torque converters. Wet clutches also can be used without a torque converter in other coupling applications. The clutch is engaged and stays locked as soon as the vehicle is launched and stays locked in all kind of driving condition. A hydrodynamic force applies force to a piston plate for the clutch in order to engage and keep the clutch locked. This hydrodynamic force results from the differential pressure between apply and release pressures on either side of the piston plate. High engine speed creates high rotational velocity at the center of the torque converter which creates a Coriolis Effect. The Coriolis Effect on the disengagement side of the piston plate causes a resistance to oil flow out of the disengagement chamber for the clutch, which increases the piston plate back pressure, that is, pressure in the disengagement chamber. The increase in the piston plate back pressure causes a decrease in the differential pressure drop and subsequent drop in clutch torque capacity. Coriolis force increases with engine speed and has a significant effect in higher engine speeds. In other words wet clutches lose torque capacity at higher engine speed because of the Coriolis Effect.
FIG. 1 is a perspective view of a prior art drive plate 1 for a torque converter including radially aligned wall 2 and through bore 9. Plate 1 can be connected to a piston plate for a torque converter clutch in the torque converter via openings 7 and can be connected to a cover for the torque converter via openings 3. Bore 9 is circular.
U.S. Pat. No. 4,951,467 teaches grooves or protrusions on a cover for a torque converter with a torque converter clutch.